Annals of medical history . surprising, since from the researchesof Walcott30 we know that jellyfishes,sea cucumbers, many types of annulates,and soft-bodied crustaceans lived f duringthe Cambrian, many millions of yearsearlier. The parasitism of animals duringthe Carboniferous was preceded by partialparasitism or commensalism of the earlierperiods, and is known to have occurredamong fossil corals (Fig. 3) of the intimate association of animals and theorigin of parasitism and commensalism dur-ing the early part of the Paleozoic has beenstudied by The reader is referredto
Annals of medical history . surprising, since from the researchesof Walcott30 we know that jellyfishes,sea cucumbers, many types of annulates,and soft-bodied crustaceans lived f duringthe Cambrian, many millions of yearsearlier. The parasitism of animals duringthe Carboniferous was preceded by partialparasitism or commensalism of the earlierperiods, and is known to have occurredamong fossil corals (Fig. 3) of the intimate association of animals and theorigin of parasitism and commensalism dur-ing the early part of the Paleozoic has beenstudied by The reader is referredto his paper for further details. 30 C. D. Walcott: Evidences of Primitive Life,Smithsonian Rep. for 1915, pp. 235-255, with John M. Clarke: The Beginnings of DependentLife, Fourth Ann. Rep., Director of Science Div.,New York State Education Dept., 1908, pp. 1-13. 382 Annals of Medical History The remains of the early vertebratesprior to the Permian have shown no note-worthy pathological lesions. There may. FiG. i. Parasitized stem of a crinoid, from theCarboniferous of Germany, showing the tumor-like mass produced by the action of the mvzostomid.(After Graff.) Fig. 2. Portion of parasitized crinoid stem, show-ing carbonized remains of the myzostomid. (AfterGraff.) Fig. 3. Section through a fossil coral, Pleurodic-Ivum problemalicum from the Lower Devonian ofFifel, showing the worm tube near the example of ancient commensalism. (AfterStromer von Reichenbach.) Fig. 4. An enlarged stem of a crinoid from theKeokuk bed-, of North America, showing thatthe enlargement has involved the plates of thestem. This specimen was thoroughly mineralizedinto a geode, so that no evidences of the parasitewere seen. One-half natural size. have been diseases among these earlyforms, but the lesions have not yet beendiscovered. We find, to be sure, certain laterally compressed fishes preserved in theattitude of the opisthotonos and pleuro-thotonos in horizons prior to the P
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